In the production of products in sausage form in tubular packagings, it is frequently desirable to obtain a product which is only partially or loosely filled therein. When dealing for example with jointing materials, such a package which is loosely filled can be opened for use without the contents unintentionally issuing therefrom upon being opened due to an elevated internal pressure. In the production of sausage products, a package which is only partially filled with sausage meat may be desirable in order to impart a cross-section different from a round cross-section to the sausage product and to stabilise it for example by cooking. For that purpose, during the cooking operation the sausage product is pressed into a suitable shape. A quadrangular or square cross-section may be desirable in the case of sausage products for example if they are intended as topping for toast. As a square cross-section is of a greater periphery than a round one, the packaging may not be filled chock-full. The filling material may also expand upon being cooked, without the risk of the packaging bursting.
Various methods are known from a practical context for the production of products in sausage form which are only loosely or partially filled, which methods provide the packaging casing or cover material that is additionally needed by pulling further packaging casing material off the supply thereof.
European patent application No 0 065 807 (U.S. Pat. No. 4,434,528) discloses a method in that a portion of a tubular packaging casing material which is closed at its front end by a clip is first filled so as to be chock-full. Displacer shears are stationarily arranged directly in front of the filling tube outlet. After the conclusion of the filling operation the displacer shears are moved between the chock-full portion of the packaging casing material and the filling tube. Arranged parallel to the conveyor path and downstream of the displacer shears in the conveyor direction is a pair of pressing jaws which then clamp the chock-full portion and move it away from the filling tube. In that operation, packaging casing material is further drawn off the supply thereof, through the stationary displacer shears. A constant internal pressure is maintained in the packaging by virtue of the pulling movement of the pressing jaws. When the packaging has reached a given length, with a predetermined amount of filling material, it is closed by fitting a second clip and separated from the rest of the supply of packaging casing material.
German patent No 3 840 522 discloses a method of forming a plaited portion on a sausage casing that accommodates sausage meat. That method is used in a sausage clipping machine that is very substantially of a conventional structure. In that case, after the sausage casing is filled with the sausage meat, two pairs of displacer shears are closed so that a portion of the sausage casing that accommodates the sausage meat and an empty portion of the sausage casing are formed. Spreading of the pairs of displacer shears then takes place, to form a plaited portion. In that operation the pair of displacer shears that are closest to the free end of the closed sausage casing are displaced along the path of advance movement of the sausage casing material in such a way that the portion of the sausage casing, which is filled with the sausage meat, is displaced in the direction of advance movement of the sausage casing material and at the same time empty sausage casing material is drawn on through the second pair of displacer shears. The empty sausage casing material that is drawn along in that operation forms a first filling material-free plaited portion which, when dealing with chock-full products, is required for fitting a closure clip and a further clip as the beginning of the next product. If there is a wish to have a sausage product that is only partially filled, the above-mentioned pair of displacer shears is displaced further along its path of advance movement. That further spreading movement, which is also referred to as overspreading, creates a filling material-free plaited portion of increased length. As soon as the desired length of plaited portion is reached, a second clip is fitted at the side of the second pair of displacer shears, being the side facing away from the first pair of displacer shears, and then the sausage casing material is cut off. That method, which in itself already operates well, uses a first drive for the first spreading movement as is necessary for closing chock-full packagings. A second drive provides for the overspreading effect, that is to say creating an elongated filling material-free plaited portion.
The aforementioned methods suffer from disadvantages. In the case of European application No 0 065 807, when dealing with a packaging of coarse-grain filling material, there is the risk that the packaging casing material is damaged upon being compressed. Apparatuses that operate in accordance with the method described in German patent No 3 840 522 use a first drive for spreading the pairs of displacer shears. As the overspreading movement represents an additional function, which is usually implemented by a subsequently fitted second drive.